From the past, there are electronic books (digital books) in which books such as printed magazines published by publishers are digitized to enable them to be browsed in electronic apparatuses such as PCs (Personal Computers) and cellular phones. The electronic books have a merit that publishers can provide contents of the books to readers at lower costs than in the case of providing printed publications, and are therefore prevailing increasingly.
When browsing such an electronic book on a display apparatus, for example, a user can turn a page or add a bookmark by performing various operations on the electronic book displayed on the display apparatus. For example, Patent Document 1 below discloses an electronic book display apparatus capable of putting, when an arbitrary element out of a plurality of elements constituting contents of a book is designated via an input means, a mark for emphasizing the designated element in accordance with a designated position in an area displaying the designated element.